When we want to incorporate FEA techniques in ouranalysis, we should consider ways to simplify our model. A bike frame has avery small thickness relative to its surface area. Therefore, we can analyzethe geometry using shells. , @; g& R1 V4 DIn SOLIDWORKS, shells are very easy to set up. With thehelp of the Shell Manager,surfaces can be given a thickness, material, offset type, and more within oneconvenient table.7 D: @2 L2 n8 W$ b% W
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Analysis (computational) times are much lower for shellsthan solid geometry.* A/ b8 @8 h! a7 Z; H
Furthermore, laminar edges (coincident surfaces) aretreated as bonded, so there is no need to worry about knitting your surfacesbefore starting your analysis. ! {) C2 ^# b4 Y K6 c! g7 S `[attach]365869[/attach]Tapered vs. Non-Tapered Head TubeThere is quite a lot of hype about ‘tapered head tubes’ inthe performance cycling world [where the bottom profile of the head tube tapersout], but how much of a difference does it actually make? To find out, I ran astatic analysis to see if there was any noticeable effect on the frame’sstiffness.) M! z% B& F, G& ~; |+ p% T: X* ^
The main forces applied to the bike are torsional andlateral forces. Therefore, we can limit our analysis to torsional and lateralstiffness.$ h' _+ r7 d- b/ Q' q; Y- F E+ w$ s
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These are simplified definitions for a body with onedegree of freedom. This can be applied to our case by analyzing the resultantdeflection in the direction of the applied force as long as one force isapplied at a time for each analysis. 3 Y O' B4 a' U0 x# I; g n, G" jFirst, let’s look at the torsional stiffness. In order tocalculate torsional stiffness (for the Head Tube) we can create a resultantplot of the circumferential deflection about the Head Tube Axis (HT AXIS).' {, F: J0 r+ S% W1 g. n- ~
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By taking advantage of the extra spaceon the non-drive side, I was able to increase the lateral stiffness of theframe by 11%.
In the next part, I will furtherimprove the performance of the frame design by using CFD (computational fluiddynamics) analysis to optimize for aerodynamic performance.
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Thank you for reading, stay tuned forthe next part!
Summary of results
Design Aspect
Change In Stiffness (%)
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Non-Circular Profile
37 (Torsional)
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Tapered Head Tube
21.5 (Torsional)
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Non-Symmetric Chain Stay
11 (Lateral)
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Seat Stay (+/- 1 mm thickness)
<<1 (Torsional/Lateral)
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Top Tube Taper (1 1/10)
3 (Torsional) , v7 Y8 @9 p R) _, f0 b* ^, _& p% n
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這篇文章給人印象深刻的不是分析，而是自行車架的3D草圖。不要抱怨軟件如何如何，還是多檢討自己吧。